1. Field of the Invention
The present invention generally relates to a support unit that is utilized in a visual inspection of display substrates. More particularly, the present invention relates to a support unit that can effectively support a display substrate having various size cell regions in the visual inspection.
2. Discussion of the Related Art
A display substrate refers to a display device having a transparent base substrate such as a glass. A liquid crystal display (LCD) device is an example of a typical display device.
An LCD device includes an array substrate having a thin film transistor (TFT), a color filter substrate having a color filter layer, and a liquid crystal layer that is interposed between the array substrate and the color filter substrate. An LCD device is formed through processes including an array process for forming the array substrate, a color filter process for forming the color filter substrate, a cell process for interposing the liquid crystal layer between the array substrate and the color filter substrate, and a module process that includes a step of attaching polarizers on outer sides of the array substrate and the color filter substrate.
Thin film patterns are formed in the array and color filter processes through depositing (or coating), photolithography including exposing and developing, and etching procedures. In addition, the cell process includes forming an alignment layer on the inner surface of each of the array substrate and the color filter substrate; rubbing the alignment layer; scattering a spacer on either the array substrate or the color filter substrate; attaching the array substrate and the color filter substrate; and interposing the liquid crystal layer by, for example, injecting the liquid crystal material between the array substrate and the color filter substrate. The array substrate, the color filter substrate, and the liquid crystal layer form an LCD panel. Moreover, the module process includes a final step in which production quality of the LCD panel is determined by inspection, polarizers are attached to the LCD panel, various circuitry is integrated with the LCD panel, and the backlight is installed.
A visual inspection of the LCD panel is performed after the cell process and before the module process. Through the visual inspection process, spots or particles that are found due to a spacer defect can be removed. The visual inspection includes preparing a support unit, disposing the LCD panel on the support unit, and setting the support unit to support the LCD panel. The visual inspection further includes radiating inspection light into the LCD panel and measuring a uniformity of inspection light that is transmitted into the LCD cell. Specifically, the LCD panel for inspecting may include polarizers on outer sides of the LCD panel. Visual inspection may be performed on the stand-alone LCD panel, or on a display substrate including the LCD panel.
FIG. 1 is a schematic perspective view of a support unit utilized in a visual inspection of a display substrate according to the related art. The display substrate (not shown) includes a transparent base substrate such as a glass.
In FIG. 1, first and second fixed bars 10 and 12 are disposed apart from each other and are oriented along a first direction. A plurality of support bars 14 are connected to both of the first and second fixed bars 10 and 12 and are oriented along a second direction crossing the first direction. The plurality of support bars 14 are movable along the first direction. In addition, a plurality of supporting means 16 that directly contact a display substrate (not shown), or the object of the visual inspection, are mounted on the plurality of the support bars 14.
FIG. 2 is a schematic plan view illustrating a support structure of FIG. 1 supporting a multi-model type display substrate according to the related art. The multi-model type display substrate may be defined as a display substrate that has multiple cell areas arranged on it for increasing space efficiency.
In FIG. 2, a display substrate 20 has a plurality of first cells 22 having a first active area AA1 and a plurality of second cells 24 having a second active area AA2 smaller than the first active area AA1. The second cells 24 may be formed to reduce a dummy region DR between the first cells 22. That is, the display substrate 20 includes first cells 22, second cells 24 and dummy region DR.
To effectively support the display substrate 20 by the support unit 18 before the visual inspection, the support bars 14 of the support unit 18 should be moved to be corresponded to the dummy region DR of the display substrate 20.
Accuracy of the visual inspection is degraded by any shielding or blocking of inspection light by the support bars 14 or the supporting means 16. This generally occurs if the support bars 14 and the supporting means 16 overlap with the active areas AA1 and AA2 of the first or second cells 22 and 24 as shown in region OP of FIG. 2. However, because the support bars 14 of the support unit 18 according to the related art move by a simple rectilinear movement, small size active areas such as the second active areas AA2 of the display substrate inevitably overlap with a portion of the support bars 14.
Therefore, there is a problem in that the visual inspection cannot be accurate because the inspection light is shielded where the support bars 14 and the supporting means 16 overlap the active areas.